/Engine/Source/Runtime/Engine/Classes/Components/SkeletalMeshComponent.h
Get the bones used by the physics asset (if any), as these have to be updated even if LODed out.
static void GetPhysicsRequiredBones ( const [USkeletalMesh](API\Runtime\Engine\Engine\USkeletalMesh) * SkeletalMesh, const [UPhysicsAsset](API\Runtime\Engine\PhysicsEngine\UPhysicsAsset) * PhysicsAsset, [TArray](API\Runtime\Core\Containers\TArray)< FBoneIndexType > & OutRequiredBones )